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Browsing by Subject "oats"

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  • Fant, Petra (2017)
    The aim of this master’s thesis was to investigate the potential of reducing enteric methane production from dairy cows by replacing barley grain with oat grain on a grass silage-based diet. The effects of grain species on in vitro methane production, digestibility, pH and volatile fatty acid (VFA) production pattern were investigated and a regression analysis was performed to entangle possible methane mitigating mechanisms of oats. The study was conducted in the laboratory at the Department of Agricultural Research for Northern Sweden in the autumn of 2016. An in vitro gas production system was applied, consisting of 16 diets with two replicates, four blanks and three runs, each with a three-day incubation time. The feed material consisted of eight varieties of barley, eight varieties of oats and timothy silage incubated at a grain/silage ratio of 1:1 on a dry matter basis. Rumen fluid was collected from two cannulated Nordic Red dairy cows after morning feeding. Gas sampling was performed at 2, 4, 8, 12, 24, 32 and 48 hours of incubation, meanwhile VFA-sampling, pH-measurements and sampling of incubation residues were performed at 48 hours. Methane production was estimated as predicted in vivo methane production and stoichiometrically predicted methane production. The in vitro digestibility was determined as true dry matter digestibility (TDMD). Content of indigestible neutral detergent fiber (iNDF) was determined by applying a 12-day in situ incubation in two Ayrshire dairy cows. Oats had a higher content of crude protein, neutral detergent fiber (NDF), iNDF and fat compared to barley, whereas barley had a higher content of starch. Replacing barley with oats decreased predicted in vivo methane production by 9% and stoichiometrically predicted methane production by 11%. Variety within grain was not found to have any significant effect on methane production. True DM digestibility and total VFA production were lower in oat-based diets compared to barley-based diets. No significant differences were observed between the diets considering VFA molar proportions. The pH was lower in barley-based diets compared to oat-based diets. True DM digestibility was the best predictor of methane production. Among grain composition parameters, iNDF content was the best predictor of methane production, followed by NDF. Crude fat content also predicted methane production relatively well. Based on the results of this experiment, it can be concluded that replacing barley grain with oat grain in the diet of dairy cows has a potential to lower methane production predicted in vitro. Furthermore, the methane mitigating effect observed in this experiment is at least partly due to the higher fat content and lower digestibility of oats compared to barley.
  • Widianarko, Clara Stella Renata (2021)
    Oat β-glucan is a non-starch polysaccharide, and it is well-known that oat β-glucan provides physiological functionalities, such as reducing glycemic response. It is proposed that the reduction of glycemic response is due to the elevation of digesta’s viscosity in the intestinal tract, which is attributed to the viscosity generated by β-glucan. An increase in viscosity of digesta is assumed to hinder starch digestion, thus reducing glucose absorption. However, it is not known whether viscous β-glucan or β-glucan gel causes such physiological responses. Thus, the aim of this Master’s thesis was to study the effects of viscous β-glucan on in vitro starch digestion. The in vitro starch digestibility method was adjusted to suit the viscous β-glucan. The hypothesis was that sample containing oat β-glucan would hinder starch hydrolysis compared to the sample without oat β-glucan. Viscosity and viscoelasticity of wheat starch were analyzed to ensure that the concentration of the wheat starch used was appropriate for the study. The viscosities of oat β-glucan solutions at different concentrations were also measured. The in vitro starch digestibility result was evaluated by measuring the concentration of starch hydrolysis product. Viscosity and viscoelasticity tests of wheat starch showed that 4% wheat starch was suitable in the starch digestibility study. The viscosities of various concentrations of oat β-glucan exhibited pseudoplastic flow behavior. In vitro starch digestibility showed that oat β-glucan slowed down the starch hydrolysis. Calcium contained in oat β-glucan was found to enhance the activity of α-amylase, resulting in a higher concentration of the starch hydrolysis product. 2160 µg/g Ca2+ was added to all samples in order to compensate for different Ca2+ concentrations in each sample. The maximum Ca2+ concentration that 1 U α-amylase could utilize was 98 µg/g Ca2+. The results of this study confirmed that the viscous oat β-glucan hindered the starch digestibility compared to the sample without oat β-glucan and calcium ions played a role in starch digestibility.